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P2P technologies, PlanetLab, and their relevance to Grid work
Matei RipeanuThe University of Chicago
1
10
100
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10000
1 10 100 1000Rank (log scale)
LinP
ack
GFL
OPS
(log
scal
e) .
2001
Why don’t we build a huge supercomputer?
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1000
10000
1 10 100 1000Rank (log scale)
LinP
ack
perf
.GFL
OPS
(log
scal
e) . 2001 2000
1999 19981997 19961995
Top500 supercomputer list over time:Zipf distribution: Perf(rank) ≈ rank -k
Parameter 'k' evolution .
-0.84-0.82-0.80-0.78-0.76-0.74-0.72-0.70-0.68
1995
1996
1997
1998
1999
2000
2001
2002
2003
Trend
Increasingly interesting to aggregate the capabilities of the machines in the tail of this distribution.
A virtual machine that aggregates the last 10 in Top500 would rank 32nd in ’95 but 14th in ‘03
Grid and P2P computing are, in part, results of this trend:Grids focus: infrastructure enabling controlled, secure resource sharing (for a relatively small number of resources) P2P focus: scale, deployability using integrated stacks.
Challenge: design services that offer the best of both worldscomplex, secure services, that deliver controlled QoS, are scalable and can be easily deployed.
Parameter 'k' evolution .
-0.84-0.82-0.80-0.78-0.76-0.74-0.72-0.70-0.68
1995
1996
1997
1998
1999
2000
2001
2002
2003
Roadmap
P2PImpactApplicationsMechanisms
PlanetLabWhy is this interesting for you?Compare resource management in PlanetLab and Globus
Wrap-Up
P2P Definition(s)
Def 1: “A class of applications that take advantage of resources (e.g., storage, cycles, content) available at the edge of the Internet.” (‘00)
Edges often turned off, without permanent IP addresses, etc.
Def 2: “A class of decentralized, self-organizing distributed systems, in which all or most communication is symmetric.” (IPTPS’02)
Lots of other definitions that fit in between
P2P impact today (1)
Widespread adoptionKaZaA – 360 million downloads (1.3M/week) one of the most popular applications ever!
leading to (almost) zero-cost content distribution:… is forcing companies to change their business models… might impact copyright laws
389,678Gnutella267,251MP2P
440,289Warez803,420iMesh
1,261,568Overnet1,987,097eDonkey2,460,120FastTrack
Sources: www.slyck.com, www.kazaa.com, July ‘04
0%
20%
40%
60%
80%
100%
Feb.'02 Aug.'02 Feb.'03 Aug.'03 Feb. '04 July'04
Other
Data transfers
Unidentified
File sharing
P2P impact today (2)
P2P – file-sharing - generated traffic may be the single largest contributor to Internet traffic todayDriving adoption of consumer broadband
Internet2 traffic statistics
Source: www.internet2.edu, July ‘04
P2P impact today (3)
A huge pool of underutilized resources lays around,users are willing to donate these resources• Seti@Home $1.5M / year in additional power consumed
which can be put to work efficiently (at least for some types of applications)
51.4 TFLOPSFloating point operations1.3K years1.3M yearsTotal CPU Time
23,3654,236,090Users764M
Total
1.13MResults received
Last 24 hours
Source: Seti@Home website, Oct. 2003
Roadmap
P2PImpactApplicationsMechanisms
PlanetLabWhy is this interesting for you?Compare resource management in PlanetLab and Globus
Wrap-Up
Applications: Number crunching
Examples: Seti@Home, UnitedDevices, DistributedSciencemany othersApproach suitable for a particular class of problems.
Massive parallelismLow bandwidth/computation ratioError tolerance, independence from solving a particular task
Problems:Centralized. How to extend the model to problems that are not massively parallel?
Relevant to Grid space: Ability to operate in an environment with limited trust and dynamic resources
Applications: File sharing
The ‘killer’ application to dateToo many to list them all: Napster, FastTrack (KaZaA, iMesh), Gnutella (LimeWire, BearShare), Overnet
Relevant to Grid space:Decentralized controlBuilding a (relatively) reliable, data-delivery service using a large, heterogeneous set of unreliable components.Chunking, erasure codes
0.8 TB/day on averageBytes transferred
~300,000Number of unique files≥ 10,000Number of local users
230,000/dayNumber of download sessions
Source: Israeli ISP, data collection 1/15-2/13/2003
FastTrack (Kazaa) load at a small ISP
Applications: Content Streaming
Streaming: the user ‘plays’ the data as as it arrives
source
Oh, I am exhausted!
Client/server approachP2P approach
Possible solution:The first few users get the stream from the serverNew users get the stream from the server or from users who are already receiving the stream
Relevant to Grid space: offload part of the server load to consumers to improve scalability
Applications: Performance benchmarking
Problem:Evaluate the performance of your service (Grid service, HTTP server) form end-user perspective
Multiple views on your site performance
Relevance to Grid space: Grid clients are heterogeneous, geographically dispersed Benchmark services for this set of consumers
End-to-end Performance Benchmarking
Back-end Infrastructure
Firewall
NetworkLandscape
Backbone
ISP
Consumer User
3rd partycontent
Web server
App server
Backbone
RegionalNetwork
Enterprise Provider
ISP
MajorProvider
Local ISP
T1
CorporateUserCorporate
Network
ComponentTesting
DatacenterMonitoring
End-to-endWeb PerformanceTesting
Database
Slide source: www.porivo.comSlide source: www.porivo.com
Many other P2P applications …
Backup storage (HiveNet, OceanStore)Collaborative environments (Groove Networks)Web serving communities (uServ)Instant messaging (Yahoo, AOL)Anonymous emailCensorship-resistant publishing systems (Ethernity, Freenet)Spam filtering
Mechanisms
To obtain a resilient system:integrate multiple components with uncorrelated failures, and use data and service replication.
To improve delivered QoS:move service delivery closer to consumer, integrate multiple providers with uncorrelated demand curves (reduces over-provisioning for peak loads)
To generate meaningful statistics, to detect anomalies:provide views from multiple vantage points
To improve scalability:Use decentralized (local) control, unmediated interactions
Roadmap
P2PImpactApplicationsMechanisms
PlanetLabWhy is this interesting for you?Compare assumptions and resource management mechanisms in PlanetLab and Globus
Wrap-Up
PlanetLab
Testbed to experiment with your networked applications.
>400 nodes, >150 sites, PlanteLab consortium: 80+ universities, Intel, HP
View presented to users: a distributed set of VMsAllocation unit: a slice = a set of virtual machines (VM), one VM at each node.
452 nodes162 sites450 research projects
VMM VMM VMM VMM
Slic
e K
OS
Slic
e K
OS
Slic
e K
OS
Slic
e K
OS
PlanetLab usage examples
Stress-test your Grid services (Globus RLS)GSLab: a playground to experiment with grid-services ‘Better-than-Internet’ services:
Resilient Overlays Multipath TCP (mTCP)Multicast Overlays
VMM VMM VMM VMMOS OS OS OS
Use
r acc
ount
Use
r acc
ount
Use
r acc
ount
Use
r acc
ount
Why should you find PlanetLab interesting?
1. Open, large-scale testbed for your P2P applications or Grid services
2. Solves a similar problem to Grids/Globus: building virtual organizations (or resource federations)
Grids: testbeds (deployments of hardware and software) to solve computational problems.
PlanetLab: testbed to play with CS applications
Main problem for both: enable resource sharing across multiple administrative domains
Roadmap
Summarize starting assumptions on: user communities, applications, resources and attempt to explain differencesLook at mechanisms to build VO.
Assumptions: User communities
PlanetLab: users are CS scientists that experiment with and deploy infrastructure services. Globus: users from a more diverse pool of scientists that are interested to run efficiently their (end-user) applications.
Implication: functionality offered
OS OS
User applications User applications
GlobusPL Services
PlanetLab.
Assumptions: Application characteristics
Different view on geographical resource distribution:
PlanetLab services: «distribution is a goal»leverage multiple vantage points for network measurements, or to exploit uncorrelated failures in large sets of components
Grid applications: «distribution is a fact of life»resource distribution: a result of how the VO was assembled (due to administrative constraints).
Implication: mechanism design for resource allocation
Assumptions: Resources
PlanetLab mission as testbed for a new class of networked services allows for little HW/SW heterogeneity.Globus supports a large set architectures; sites with multiple security requirements
Implications: complexity, development speed
Assumptions: Resource ownership
Goal: individual sitesretain control over their resourcesPlanetLab limits the autonomy of individual sites in a number of ways:
VO admins: Root access, Remote power buttonSites: Limited choice of OS, security infrastructure
Globus imposes fewer limits on site autonomyRequires fewer privileges (also can run in user space, )
PlanetLab emphasizes global coordination over local autonomy to a greater degree than Globus
Implications: ease to manage and evolve the testbed
PlanetLab
Globus
Individual site autonomy
Con
trol a
t VO
leve
l
Building Virtual Organizations
Individual node/site functionalityMechanisms at the aggregate level
Security infrastructureDelegation mechanisms
Resource allocation and schedulingResource discovery, monitoring, and selection.
Delegation mechanisms:Identity delegation
GlobusImplementation based on delegated X.509 proxies
PlanetLabNone
Broker/scheduler usage scenario:User A sends a job to a broker service which, in turn, submits it to a resource. The resource manager makes authorization decisions based on the identity that originated the job (A).
Broker
X.509/SSL
Delegated identity
Delegation mechanisms: Delegating rights to use resources
PlanetLabIndividual nodes managers hand out capabilities: akin to time-limited reservationsCapabilities can be traded Extra layer to: provide secure transfer, prevent double spending, offer external representation
GGF/GlobusWS-Agreements protocols:
To represent ‘contracts’ between providers and consumers.Local enforcement mechanism is not specified
The two efforts are complementary!
Broker/scheduler usage scenario:
User A acquires capabilities from various brokers then submits the job.
Delegated usage rights
BrokerResource
usage rights
Job descriptions +Usage rights acquired
Global resource allocation and scheduling
PlanetLabGlobus
Users
Application Managers
Brokers / Agents
Node Managers
Nodes(Resources)
• Resource usage delegation• Sends capabilities (leases)
• Identity delegation• Sends job descriptions
VO
ComputeCenter
VO(policies)
VOUsers
Services (runningon user’s behalf)
Access rights
Access
CAS or VOMSissuing SAMLor X.509 ACs
SSL/WS-Securitywith ProxyCertificates
Multiple VOs
Wrap-up
Scale & volatility
Functionality &infrastructure
Grids
P2P
Convergence: Large, Dynamic, Self-Configuring Grids
Large scaleIntermittent resource participationLocal control, Self-organizationWeaker trust assumptionsInfrastructures to support diverse
applicationsDiversity in shared resources
Fin
Links to papers, tech-reports, slides:Distributed Systems Group @ UChicago
http://dsl.cs.uchicago.edu
Thank you.
User
Userprocess #1
Proxy
Authenticate & create proxy credential
GSI(Grid
Security Infrastruc-
ture)
Gatekeeper(factory)
Reliable remote
invocation
GRAM(Grid Resource Allocation & Management)
Reporter(registry +discovery)
Userprocess #2Proxy #2
Create process Register
GT2 in One SlideGrid protocols (GSI, GRAM, …) enable resource sharing within virtual orgs; toolkit provides reference implementation ( = Globus Toolkit services)
Protocols (and APIs) enable other tools and services for membership, discovery, data mgmt, workflow, …
Other service(e.g. GridFTP)
Other GSI-authenticated remote service
requests
GIIS: GridInformationIndex Server(discovery)
MDS-2(Monitor./Discov. Svc.)
Soft stateregistration;
enquiry